Re: Top 10 most common hard skills listed on resumes...

Waldek Hebisch <antispam@fricas.org> writes:

Keith Thompson <Keith.S.Thompson+u@gmail.com> wrote:

Waldek Hebisch <antispam@fricas.org> writes:

Bart <bc@freeuk.com> wrote:

[...]

I had a problem with this code because it was so verbose. The first
thing I did was to define aliases u64 and u32 for those long types:
 
 typedef unsigned long long u64;
 typedef unsigned long u32;

>
This code runs in 33 bit i386, 32 bit ARM and 64 bit x86-64, in
all cases under Linux.  As Keith noticed, most popular of those
has 64-bit long.  So your definition would break it.  You need
>
typedef unsigned int u32;

 
Just add #include <stdint.h> and use uint32_t -- or, if you value
brevity for some reason:
 
    typedef uint32_t u32;
 
(Bart dislikes <stdint.h>, but there's no reason you should.)

>
1. Well, I used to care about pre-Ansi compilers and for benefit
to them I got into habit of avoiding <stdint.h>.  Yes, it is time
to change and on microcontrollers I use <stdint.h> as sizes
are important there and I do not expect to ever compile
microcontroller code with non-Ansi compiler.

Pre-ANSI?  I haven't been even been able to find a working pre-ANSI
C compiler.

<stdint.h> was added in C99, so a C89/C90 ("ANSI") implementation might
not support it, but I'd still be surprised if you could find a C
implementatation these days that doesn't have <stdint.h>.  And you can
roll your own or use something like
<https://www.lysator.liu.se/c/q8/index.html>.

2. As I explanined fixed size is just current state of developement.
On 64-bit machines code should use bigger types.  And to get
128-bit type it seems that I need nonstandard type (there seem
to be new types in C23, but I did not investigate them deeper).

C23 doesn't add any new support for 128-bit integers.

gcc (and compilers intended to be compatible with it, like clang)
support __int128 and unsigned __int128 types, but only on 64-bit
systems, and they're not strictly integer types (for example, there are
no constants of type __int128).

It might still make sense to define your types (which might be 32 or 64
bits) in terms of the fixed-width types in <stdint.h>.  Without knowing
the details, it's hard to know just how you should approach it.

--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */